The present invention relates to cosmetic and therapeutic compositions for the lips containing one or more acids. More particularly, the present invention relates to lip compositions comprising an acid that exhibit a sour taste.
Unprotected skin is very susceptible to drying out and becoming irritated from exposure to the elements. This is especially true with regard to the lips, which have been found to be even more vulnerable to water loss than typical skin. This is due, in part, to the fact that the lips have a thinner stratum corneum, the outermost of three layers comprising skin, and contain a lesser amount of lipids than skin on other parts of the body. When the lipid barrier is depleted or inadequate, lips dry out, becoming irritated and prone to cracking. Lips are susceptible to other harms as well. For example, due to the fact that lips contain less melanin than other areas of skin, they are at risk of sunburn and UV damage.
In response to this, there have been various products introduced by manufacturers to keep the lips in a moisturized, smooth condition and protected from damage. These products most typically contain waxes or oils that mitigate the amount of moisture that escapes from the lips into the atmosphere. Some products may additionally contain moisturizers as well as healing agents to actually replace the moisture that has been lost and/or sooth damaged lips. Various sunscreens are also added to some products to protect the lips from sun damage.
Although useful, the taste and/or consistency of these products often does not appeal to consumers, especially younger users in their adolescent and teenage years. These users often want a tasteful and long lasting lip product that can easily be reapplied as desired. It has been found that slightly sour tasting candies and other products are pleasant to many consumers and in great demand. One only need consider the great variety of sour tasting candy and beverages now on the market to realize this. These products are typically given their sour taste by incorporating a small amount of acid, typically one or more fruit acids, into the product formulation. These acids stimulate taste receptors mainly along the sides of the tongue that are sensitive to such compounds. The concentration of acid in these products must be carefully controlled, great enough such that a pleasant xe2x80x9ctanginessxe2x80x9d is provided, but not so great that the acid burns or irritates the mouth.
The use of some types of acids in skin products is known. For example, it is known to use various alpha-hydroxy acids in skin lotions and creams to accelerate skin cell turnover by chemically exfoliating the top layer of skin cells. (See, e.g., U.S. Pat. No. 5,939,085). These products, however, are designed to achieve practically the exact opposite result of the present invention. Whereas the present invention is designed as a humectant and moisturizer and uses a relatively small amount of acid as a gentle flavoring agent, the hydroxy acid containing products are used to treat acne and other skin conditions by removing the cells from the skin surface using an astrigent acid-based composition, in effect xe2x80x9cburning offxe2x80x9d the upper skin layer. The use of such products on the delicate skin of the lips would be extremely discomforting.
With the great demand for sour tasting products, a need exists for a sour tasting lip product that can easily be reapplied, will not irritate the lips when used as directed, can be formulated with various lip moisturizers and protectors, and that is relatively stable over extended periods of time.
The present invention provides a method for making a sour tasting lip product containing one or more acids dissolved in a base composition, and the products formed thereby. The acids used in the invention are generally any of the naturally occurring fruit acids, although other acids may also be used.
Anhydrous acids are first dissolved in a suitable solvent, such as propylene glycol, under heat and stirring. Preferably the solvent and other components of the composition are substantially anhydrous. As used herein, xe2x80x9csubstantially anhydrousxe2x80x9d means containing less than about 5% water by weight. After the acid is fully dissolved, a suitable cosmetic lip base is added to the mixture. As used herein, xe2x80x9ccosmetic basexe2x80x9d refers to any cosmetically or pharmaceutically acceptable carrier or base composition suitable for use in lip glosses, lip balms, lipsticks, and other compositions appropriate for application on the lips and around mucous membranes. This base may contain any of a number of known ingredients, such as various oils, moisturizers, emollients, etc., in any concentration that does not adversely affect the properties of the final composition. Other components may also be added, such as vitamins, sweeteners and other flavorings, sunblock agents, colorants, etc. The final composition is mixed to form a homogenous composition of the desired consistency.
Depending on the type of flavoring added to the mixture, the final composition will typically have a tart, sour fruit taste. The content of the final composition is preferably about 2% to about 25% by weight acid, about 3% to about 25% solvent, about 1% to about 10% flavoring, and about 55% to about 85% cosmetic lip base. The final composition will preferably have a pH of about 2.00-4.00. Although the final composition may be formulated to have any consistency desired, the lip composition produced by the present invention will typically have a consistency similar to that of a heavy lotion or skin cream. Therefore it may easily be stored in small cosmetic bottles and applied to the lips using an applicator colloquially known as a xe2x80x9cdoe-footxe2x80x9d applicator. This type of applicator consists of a small absorbent tip on the end of a thin tubular body. The absorbent tip is dipped in the composition and then dabbed on the lips, transporting the composition from the tip to the lips.
The present invention provides a process for producing sour tasting cosmetic lip products containing one or more acids dissolved in a cosmetic lip base composition, and the products formed from this process. Other ingredients may be incorporated into the lip products of the present invention, including, but not limited to, moisturizing aids, vitamins, and sunblocks.
The acids suitable for use in the present invention include any acid that will produce a stable mixture and a sour flavor when combined in specific concentrations with a cosmetic lip base composition, but, when combined in a final product, will not burn the lips or mouth even after heavy use. By xe2x80x9cheavy usexe2x80x9d, the applicants are generally referring to continuous extended exposure of 24 hours or greater and/or repeated applications within that time. Preferably, the acids used in the present invention include one or more of the acids naturally occurring in various fruits, including but not limited to citric acid, malic acid, tartaric acid, fumaric acid, propionic acid, acetic acid, and lactic acid. These acids are weaker than some of the stronger mineral acids, such as hydrochloric acid, and produce a pleasing sour taste, especially when combined with complementary fruit flavorings in the final composition. Therefore, although other acids are contemplated by the invention, fruit acids will be used in all subsequent discussion for clarity and convenience. Similarly, while the subsequent discussion may refer to a single acid, it must be remembered that any combination of one or more fruit acids may be used in formulating a composition according to the present invention. A preferred formulation of acids for use in the present invention is citric acid or a combination of citric acid with one or more other fruit acids. Preferably, the total amount of acid in the final product is from about 2% to about 25% by weight, more preferably about 2% to about 15% by weight. In the case of the use of multiple acids, the combined amount of all such acids will fall within these concentration ranges. The final composition will typically have a pH of about 2.00-4.00, and preferably about 2.68-3.90. In the case of an anhydrous final composition, pH is measured on a 5% by weight aqueous solution of the composition.
The acids for use in the present invention are typically USP grade (99%+pure) and purchased in powder form. These acids are available from various companies such as Aldrich Chemical Co., Milwaukee, Wis. To produce more uniform mixing and promote better consistency in the final composition, the acid is preferably dissolved in a solvent prior to mixing with a cosmetic lip base. Suitable solvents include any solvents in which the selected powder acid is soluble and which are themselves soluble in the cosmetic lip base. Preferable solvents include compounds that allow for dissolution of the relatively polar acids while being easily incorporated themselves into the generally non-polar cosmetic base. Thus, preferred solvents include, but are not limited to glycerin, propylene glycol, dipropylene glycol, butylene glycol and its higher homologues. In addition to being somewhat sweet and thus enhancing the flavor of the final composition, these solvents readily dissolve the acids upon heating and are easily incorporated into a typical cosmetic lip base. A most preferred solvent is propylene glycol. The use of water as a solvent, although workable and contemplated by the invention, is not preferred, since the reactivity and stability of the acid in the final composition becomes more difficult to control, which may lead to a burning sensation on the lips and mouth. Preferably, the total amount of solvent in the final product is from about 3% to about 25% by weight, more preferably about 5% to about 20% by weight.
Suitable cosmetic lip bases for the present invention may include any compositions useful in cosmetic lip products that are compatible with the acid and solvent used in formulating the invention. Cosmetic bases in the present invention may include various ingredients that find use in lip glosses, lip balms, lipsticks, lip moisturizers, and other lip products in any concentration that does not adversely affect the sour flavoring and other properties of the final composition. Thus, ingredients suitable for use in the cosmetic bases of the present invention may include, but are not limited to, various oils, waxes, humectants, emollients, proteins, preservatives, antioxidants, emulsifiers, sunblocks, colorants, fragrances, moisturizers, healing agents and vitamins.
xe2x80x9cOilsxe2x80x9d as used herein encompass not only naturally occurring plant, animal and mineral oils, but also oil-like emollients such as fatty esters, fatty alcohols and silicone oils. Suitable moisturizers and oils include, but are not limited to, polybutene; lanolin; petrolatum; vegetable oil; mineral oil; castor oil; isopropyl palmitate; diisopropyl dimerate; glycerides, triglycerides and other esters; glycerols; diglycerols; olive oil; vitamin E acetate; and mixtures thereof.
xe2x80x9cWaxesxe2x80x9d as used herein encompass not only those plant, animal and mineral waxes containing esters of fatty acids and alcohols and saturated hydrocarbons, but also synthetic resins having a wax-like texture, such as silicone waxes. Suitable waxes include, but are not limited to, beeswax; paraffin wax; lanolin wax; jojoba wax; carnauba wax; spermaceti; ozokerite; candellila wax; animal wax; synthetic wax; plant and mineral waxes; and mixtures thereof.
Suitable healing agents or other active ingredients suitable for use in the present invention include, but are not limited to, aloe vera; elastin; collagen; vitamin E and derivatives thereof; vitamin C and derivatives thereof; vitamin A and derivatives thereof; allantoin; calamine; dimethicone; cocoa butter; shark liver oil; botanical extracts; phospholipids; and mixtures thereof.
Other materials suitable for use in the present invention and specific formulations are disclosed in xe2x80x9cCosmetics: Science and Technologyxe2x80x9d, 2nd Ed., Vol. 1, Wiley lnterscience, 1972, and xe2x80x9cThe Chemistry and Manufacture of Cosmeticsxe2x80x9d, 2nd Ed., Vol. IV, chapter 44, M. G. DeNavarre, Continental Press, 1975, the disclosures of which are incorporated herein by reference.
Preferably, the cosmetic base will contain polybutene and mineral oil. The use of greater than negligible amounts of water in the cosmetic base, while contemplated, is not preferred, for the same reasons that water is not a preferred solvent, as stated above. Preferably, the total amount of cosmetic base in the final product is from about 55% to about 90% by weight, more preferably about 60% to about 85% by weight.
In addition to the acid, solvent, and cosmetic lip base, other ingredients may be added to the lip compositions of the present invention. These ingredients may be part of the cosmetic base, or they may be added separately. Typically, for ease of production, these ingredients are those components that are only desired in specific formulations of the present invention. The cosmetic base and other ingredients may be combined into a bulk base. In this way, only a single cosmetic base is needed, which can be used for all formulations, while those additional ingredients only desired in specific instances may easily be added or have their concentration changed without altering the cosmetic base. Representative ingredients that may typically be added to the composition separately from the cosmetic base include, but are not limited to, artificial and natural sweeteners, TiO2, and artificial and natural flavorings.
In a preferred embodiment, an artificial sweetener or sugar by-product that exhibits a sweetness anywhere from 10 to 500 times greater than natural sugar is added to the composition as a flavor enhancer, along with one or more proprietary flavorings available from various sources. Although sugar may be used as a sweetener, a proprietary flavor enhancer is preferred since they generally exhibit better long-term stability and greater resistance to microbial buildup. A preferred sweetener for use in the present invention is xe2x80x9cFlavor Enhancerxe2x80x9d, available from Noville, Inc.
TiO2 is both a whitening agent and a sunblock and may be added in varying amounts, depending on the amount of whitening and SPF protection desired in the final formulation. Preferably, the total amount of proprietary flavoring in the final product is from about 1% to about 10% by weight, more preferably about 1% to about 7% by weight. Preferably, the amount of sweetener added is an amount necessary to impart, in conjunction with the acid, a pleasing sour taste to the final composition that is similar to various commercially available sour candies. Typically, depending on the sweetener, this may be from about 0.05% to about 2.00% by weight.
There are various methods to manufacture the compositions of the present invention. As stated earlier, the acid is preferably dissolved in a solvent prior to being combined with the cosmetic base and other ingredients. To begin the process, a production vessel is filled with solvent and the requisite amount of acid is added to it. The mixture is agitated or stirred to effectuate mixing until the acid is completely dissolved in the solvent and forms a solution. Depending on the solvent, the solvent can be heated to facilitate dissolution of the acid. Typically, with the use of propylene glycol as the solvent, the solvent is heated to between about 80xc2x0 and 90xc2x0 C. and stirred for about 30 to 60 minutes. Once the acid is completely dissolved, the cosmetic lip base and other ingredients that are to be incorporated into the final composition are added to the solution. Preferably, the cosmetic base is added first and mixed thoroughly followed by the other ingredients. Depending on one""s perspective, the solution can be thought of as being dissolved in the cosmetic base, or vice versa. Both expressions are synonymous as used herein, and refer to the combining of the two materials to form a substantially homogeneous mixture. The mixture is then stirred to completely dissolve the components and create a homogenous final composition. Depending on the actual ingredients used in a specific formulation, this composition may be a high quality suspension.
Depending on the exact composition of the cosmetic base and the concentration of ingredients, the final composition may have a consistency of anything from a conventional lipstick or hard wax to a thin cream. A typical composition according to the present invention will have a consistency similar to petrolatum or a thick cream with a viscosity of about 19560 centipoise as measured using a No. 4 spindle at 30 rpm and 25xc2x0 C. and a specific gravity of about 0.88-0.92 g/ml. In this respect, a xe2x80x9cdoe-footxe2x80x9d applicator is useful in applying the composition. Although colorants may be added to the composition as described above to give the composition any color desired, added TiO2 will give the composition an opaque white color that applies as a substantially clear layer on the lips in the absence of any added colorants.